Tumour markers in neuroendocrine tumours

Most of the neuroendocrine tumours produce and secrete a large number of pe ptide hormones and amines. Each of these substances cause a specific clinic al syndrome: carcinoid, Zollinger-Ellison, hyperglycaemic, glucagonoma and WDHA syndrome. Specific markers for these syndromes are basal and/or stimul ated levels of: urinary-5-HIAA, serum or plasma gastrin, insulin, glucagon, and VIP, respectively. About 1/3 of neuroendocrine tumours belong to the s o-called "non-functioning" rumours. Therefore, general markers such as chro mogranin A, pancreatic polypeptide, serum neuronspecific enolase and subuni t of glycoprotein hormones have been used for screening purposes in patient s without distinct clinical hormone related syndromes. Among these general tumour markers chromogranin A, although its precise function is not yet est ablished, has been shown to be a very sensitive and specific serum marker f or various types of neuroendocrine tumours. This is because it may also be increased in many cases of less well differentiated tumours of neuroendocri ne origin that do not secrete known hormones. Then chromogranin A is consid ered the best general neuroendocrine serum or plasma marker available at th e moment and is increased in 50-100% of patients with various neuroendocrin e tumours. Chromogranin A serum or plasma levels reflect tumour load and ma y be an independent marker of prognosis in patients with midgut carcinoids.